1. Field of Invention
This invention relates generally to insecticidal compositions and methods of using same to control various crawling and flying insect pests, and, in its preferred embodiments, relates more particularly to a combination of synergistic non-poison insecticides by themselves and in combination with a known poison insecticide at a greatly reduced concentration, and adapted to unexpectedly increase insect mortality and reduce kill time.
2. Description of Prior Art
Commercially available insecticides, including those available for home use, commonly comprise active ingredients or poisons which are not only toxic to the target insect pests, but, if used in relatively confined environments and delivered as aerosol sprays, can be present in sufficient concentration to also be toxic to humans and household pet. Various undesirable side effects may include immediate or delayed neurotoxic reactions, and/or suffocation. Even the noxious odor of such materials can cause headaches or upset stomachs in some individuals. These adverse side effects are exacerbated when such compositions come in contact with persons of increased sensitivity, or persons of small body mass such as children or babies.
For some time, efforts have been made to develop insecticidal compositions, particularly, those intended for residential use in aerosol form, which are effective in killing the targeted insect pests completely and quickly, but non-toxic to humans and pets. The Environmental Protection Agency (EPA) regulates the use of potentially toxic ingredients in pesticidal compositions under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). Certain materials considered to be either active or inert materials by the EPA have been deregulated or otherwise identified as acceptable safe substances under FIFRA offering minimum risk in normal use. Other materials are currently undergoing investigation and may be deregulated in due course. Consumers generally consider deregulated substances non-poisonous. Thus, the term non-poisonous as used herein is intended to convey a compound or composition that, while highly effective in killing targeted insect pests, is safe to use around humans, particularly small children, and pets.
Among the insects that are found to be particularly undesirable are cockroaches, both the American and German species. These pests shed their skin, which, over time, disintegrates forming what is known as cuticle in the air, a particular problem for people suffering from asthma. Thus, not only is it important to kill cockroaches with an effective insecticide, but also the kill time must be sufficiently short for the carcass to be properly disposed of before the insect can crawl into a remote area to die.
While cockroaches are a prime target for a household spray, for general application such materials must also be effective against other crawling insects, such as ants, water bugs, silverfish, crickets, spiders and centipedes. Additionally, aerosol compositions of such insecticides of proper concentration must also be effective against various flying insects, including flies, mosquitoes, gnats, moths, wasps, hornets, yellow jackets and other bees, both inside and outside of the house.
One of the materials exempted by the EPA under FIFRA is cornmint oil (also known as Japanese mint or Mentha arvensis). Cornmint oil includes a high concentration of menthol and is known to contain alpha-pinene, myrcene, limonene, gamma-terpenine, 3-octanol, menthofuran, beta-caryophyllene, germa-crene D and beta-pinene, along with other components. As with other mint oils, cornmint oil has been used as a flavoring agent in mouthwashes, cough syrups, throat lozenges, chewing gum, and the like.
Recently, it has been found that when cornmint oil was combined with a synergist such as sodium lauryl sulfate (“SLS”), cornmint oil became a highly effective insecticide against common household pests such as American and German cockroaches and black ants. These findings are described in U.S. Pat. No. 5,998,484 (the “'484 patent”), assigned to Woodstream Corporation. These findings were surprising because prior to the '484 patent, cornmint oil had not been shown to be particularly effective, and certainly was not distinguished from other materials of this kind as a candidate for special attention.
Other essential oils currently deregulated by the EPA under FIFRA include cedar oil, cinnamon oil, citronella oil, clove oil, corn oil, garlic oil, lemongrass oil, linseed oil, peppermint oil, rosemary oil, soybean oil and thyme oil. Among the essential oils proposed for exemption from registration are a number of the citrus oils. Citrus oils would include orange oil, lemon oil, lime oil, grapefruit oil and tangerine oil.
As with cornmint oil, it was also recently discovered that many of these other deregulated essential oils which had not been previously shown to be particularly effective as active ingredients, by themselves, were in fact effective insecticidal compositions when combined with a synergist such as lecithin or SLS. These insecticidal compositions can be found in U.S. Pat. No. 6,548,085, also assigned to Woodstream Corporation.
Pyrethrum is a natural plant oil that occurs in the Pyrethrum daisy, Tanacetum cinerariaefolium, a member of the chrysanthemum family (Chrysanthemum cinerariaefolium). It is found mainly in tiny oil-containing glands on the surface of the seed case in the tightly packed flower head. Pyrethrum flowers are also known as Dalmatian Insect powder and Persian Insect powder. Several trade names associated with these compounds are Buhach, Chrysanthemum Cinerariaefolium, Ofirmotox, Insect Powder, Dalmation Insect Flowers, Firmotox, Parexan and NA 9184. The flowers of the plant are harvested shortly after blooming and are either dried and powdered or the oils within the flowers are extracted with solvents. The resulting mixture of pyrethrin containing dusts and extracts usually have an active ingredient content of about 30%. These active insecticidal components of pyrethrum are collectively known as pyrethrins. Two pyrethrins are most prominent, pyrethrin-I and pyrethrin-II. The pyrethrins include other active ingredients such as Cinerin I and II, Jasmolin I and II, pyrethrosin, pyretol, pyrethrotoxic acid, chrysanthemine, chrysanthemumic acid. See, Merck Index, Eleventh ed., (1989).
Pyrethrin compounds have been used primarily to control human lice, mosquitoes, cockroaches, beetles and flies. Some “pyrethrin dusts,” used to control insects in horticultural crops, are only 0.3% to 0.5% pyrethrins, and are used at rates of up to 50 lb/Acre. Other pyrethrin compounds may be used in grain storage and in poultry pens and on dogs and cats to control lice and fleas. However, the natural pyrethrins are contact poisons which quickly penetrate the nervous system of the insect. A few minutes after application, the insect cannot move or fly away. The natural pyrethrins can be swiftly detoxified by enzymes in the insect. Semisynthetic derivatives of the chrysanthemumic acids have been developed as insecticides. These are called pyrethroids and tend to be more effective than natural pyrethrins while they are less toxic to mammals. One common synthetic group of pyrethroid compounds are the allethrins, also known as allyl cinerins (allethrin I and II).
Pyrethrum was used commercially many years ago as an insecticide, primarily in the form of “oleoresin of pyrethrum”. Oleoresin of pyrethrum is an archaic pharmaceutical term for an ether extract of the cinerariaefolium variety of chrysanthemum. It contains volatile oils and components having insecticidal properties, called pyrethrins, jasmolins, and cinerins. These materials are known to be toxic to insects, essentially non-toxic to mammals, to lack persistence in the environment, and to be characterized by negligible biological magnification in the food chain.
As used herein, the term “pyrethrins” is intended to mean pyrethrin and its active components. One of the problems with using pyrethrins as insecticides is their high cost per unit dose. An example of such a composition comprising a mixture of saponified organic acids, i.e., salts of coconut oil, and pyrethrins was sold commercially under the trademark Red Arrow about 55 years ago. However, these mixtures did not solve the expense problem because of their high pyrethrin content, about 40% by weight, and because the coconut oil soaps contributed little to their insecticidal efficacy. In fact, most commercially available fatty acid soap compositions contain an excess of alkali which is thought to promotes hydrolysis and inactivation of pyrethrins. Pyrethrin-based insecticides also degrade rapidly in storage and in use.
More recently, the commercially effective use of pyrethrins was shown when pyrethrins were combined with certain fatty acid salts and a low molecular weight alcohol, such as isopropanol. See for example, U.S. Pat. Nos. 4,904,645, and 4,983,591.
Insect killing soap has also been sold commercially as an insecticide for many years. An example is the Safer® Brand Insect Killing Soap Formulation. This insecticide soap formulation contains about 49.52% potassium salts of fatty acids by weight, and was used to formulate treatments containing about 1.0% to about 2.0% potassium salts of fatty acids by weight. Insecticidal soap has also been shown to have synergistic effects when combined with an insecticide, i.e. pyrethrin, and the soap and compositions of soap and pyrethrins are described in U.S. Pat. Nos. 4,861,762, 4,983,591 and 5,047,424. These three patents, as well as U.S. Pat. Nos. 6,548,085, and 5,998,484 which describe the combination of essential oils and a synergist, are all incorporated by reference herein as if fully set forth in their entireties.